Field of the Invention
The present invention relates to activation control for an image reading apparatus.
Description of the Related Art
Image processing apparatus, such as copying machines and facsimile machines, include an image reading apparatus, for example, a scanner, which is configured to obtain image data by optically reading an image of an original. In recent years, it has been desired that the first copy output time (FCOT), namely, the time taken from the issuance of an instruction to start copying until one sheet is output, be shortened, and that the processing speed in operation of the apparatus be increased. It is also desired that the time taken from the power of the image reading apparatus being turned on until the image reading apparatus is usable, namely, the time taken from the power supply being turned on until activation processing for the image reading apparatus finishes (hereinafter referred to as “activation time”), be shortened.
As a way to increase the processing speed, the read speed of control programs may be increased. Image reading apparatus include a read-only memory (ROM) and a random-access memory (RAM). The control programs are stored in the ROM, but the RAM reads data stored in its memory faster than the ROM reads data stored in its memory. Therefore, during activation of the image reading apparatus, the control programs stored in the ROM are transferred to the RAM, and after the transfer is complete, the control programs are read from the RAM for execution. As a result, compared with when the control programs are directly read from the ROM for execution, the time required to read and execute the control programs can be shortened, namely, the processing speed can be increased.
The RAM is a volatile memory, and thus, when the power supply to the RAM is stopped, the data stored in the RAM is lost. As a result, it is necessary to transfer the control programs from the ROM to the RAM each time the image reading apparatus is activated. However, when all of the control programs are transferred and then the control programs are read from the RAM for execution, compared with when the control programs are not transferred and are read from the ROM for execution, the activation time is elongated by the amount of time taken to transfer the control programs.
In Japanese Patent Application Laid-Open No. 2013-97715, there is proposed a technology for shortening the activation time by reading the control programs from the ROM for execution in parallel with transferring the control programs from the ROM to the RAM. After the transfer of the control programs is complete, the processing speed can be increased by switching the control program read destination from the ROM to the RAM.
In Japanese Patent No. 4111649, there is proposed a technology for reading and executing, in a digital camera in which a mode is specified during activation, a portion of the control programs that is shared by each mode, then determining the specified mode, and reading and executing a required portion of the control programs in accordance with the mode. More specifically, in Japanese Patent No. 4111649, when a photography mode is specified during activation, the portion of the control programs required for the photography mode is read and executed. When a playback mode is specified during activation, the portion of the control programs required for the playback mode is read and executed. With this technology, compared with reading all of the control programs, the activation time can be shortened by the time saved by not reading the portion of control programs that is unnecessary for the specified mode.
The image reading apparatus may be activated as a result of “power supply ON”, in which the power supply to the whole apparatus is turned on, or as a result of “return from sleep (i.e., a non-operating state for saving power by stopping the power supply to a portion of the apparatus during a period in which the apparatus is temporarily not in use; a power-saving state)”. In order to allow the user to use the apparatus more conveniently, it is necessary to increase the processing speed and shorten the activation time at the same time for both of those cases. Problems involved with increasing the processing speed while also shortening the activation time are now described below.
In the technology described in Japanese Patent Application Laid-Open No. 2013-97715, the processing speed can be increased compared with when the control programs are directly read from the ROM for execution after transfer of the control programs is complete and the control program read destination is switched from the ROM to the RAM. However, during the transfer of the control programs, namely, before the control program read destination is switched from the ROM to the RAM, the processing speed has a possibility of becoming slower conversely. The reason for this is that in the technology described in Japanese Patent Application Laid-Open No. 2013-97715, during transfer of the control programs, the transfer of the control programs from the ROM to the RAM and the reading of the control programs directly from the ROM for execution are performed in parallel. As a result, when there is a conflict between access to the ROM for transferring a control program and access to the ROM for reading and executing a control program, one of the processes has to wait.
In the technology described in Japanese Patent No. 4111649, after the power supply is turned on, first, a portion of the control programs that is shared by each mode is read. However, when the shared portion is large, the reading takes time, and the activation time is only shortened by a small amount. During activation, image reading apparatus have a “power supply ON” mode and a “return from sleep” mode. The processing that needs to be performed during activation is the same for the “power supply ON” mode and the “return from sleep” mode. As a result, the required control programs are also the same, and hence the technology described in Japanese Patent No. 4111649 cannot be applied to image reading apparatus.